diff --git a/daemon/mgmt/manager-base.hpp b/daemon/mgmt/manager-base.hpp
index 8fb8cd3..78c6efe 100644
--- a/daemon/mgmt/manager-base.hpp
+++ b/daemon/mgmt/manager-base.hpp
@@ -19,6 +19,11 @@
 class ManagerBase
 {
 public:
+  struct Error : public std::runtime_error
+  {
+    Error(const std::string& what) : std::runtime_error(what) {}
+  };
+
   ManagerBase(shared_ptr<AppFace> face);
 
   virtual